Charities would not normally hold such assets as 
investments but only for their functional use. In this case 
value at either their depreciated historical cost or their 
depreciated estimated value in use or other acceptable 
basis of valuation the trustees decide on - which does not 
have to be "market value

the value shall be assessed as follows:
    cost incurred to purchase
   +any legal charges
   +any cost to get it into working condition.

such assets shall be amortised over a period of 10 years(as 
per AS26).. however assets like websites etc can be 
amortised in a shorter period....